Code reader
 

It's been 20 years and 155,000 miles trouble free with the 2003 Freightliner Columbia with a Mercedes MBE4000. It's throwing a code, but I don't have a reader to check it out. Does anyone have a source for a code reader for this engine? It only happens at start up and maybe lasts 15 or 20 minutes driving down the road. The check engine light randomly flashes, but not like it's a number code unless there are a bunch of them and I'm missing the count. There are no other signs of engine issues. Engine runs fine, Meritor tyranny shifts like it always did. After 15, 20 minutes down the road, the flashing stops and all is well. I was thinking maybe it had something to do with a coolant level or some other fluid, but everything is good. Any ideas on what's happening or a code reader? Thanks.